1. Field of the Invention
The present invention relates to aircraft flight controls for improving lateral control and roll rate of an aircraft, and more particularly to auxiliary flight control flaps usable in conjunction with an aircraft aileron roll control system to augment lateral or roll control effectiveness at high dynamic pressures.
2. Description of the Prior Art
An aerodynamic problem that has long plagued aviation concerns lateral control of aircraft at transonic speeds and high dynamic pressures. In the lateral control of an aircraft during turn and roll maneuvers, for example, conventional ailerons are employed, and generally are adequate for aircraft employing relatively thick wings. However, the effectiveness of ailerons on aircraft having relatively thin wings is severely reduced or impaired during maneuvers at high dynamic pressures. Moreover, it is well known that supersonic aircraft can suffer control reversal at transonic speeds, which can have an adverse effect on lateral control and rate of roll of the aircraft.
The use of conventional ailerons on thin wing combat aircraft requires additional structural weight in the wings to obtain the rigidity necessary to achieve the required roll rate or time to achieve a given bank angle.
A number of devices have been proposed to overcome the problem discussed above, some of which have been, and now are employed on aircraft; such as multiple and single spoilers, spoiler and aileron/flap combinations, all of which impose penalties of one kind or another on the overall efficiency of the wings during normal flight since it is not practicable to maintain aerodynamic smoothness or surface continuity on the wing surfaces with such devices, for normal flight.
In addition, such devices tend to be unduly complex, expensive, and frequently substantially reduce the structural strength of the wings. Also, the more complex devices are subject to malfunction or possible failure.
Contemporary military aircraft designed for sustained supersonic flight requires wings with ultra-thin sections that obviously limit the options available in the use of prior known auxiliary aircraft control devices.
However, improvements have been made in design of auxiliary devices to enable better and more effective control of the aircraft during high stress manuevers, such as rolls. Most modern high speed aircraft are affected by the degree of structural distortion or deformation of the wing and other aircraft components. The interaction of the aerodynamic forces and the structural deformation is termed "aeroelastic effect." Due to this effect, certain aircraft designs must lock out aileron control above certain speeds because the ailerons contribute roll in the "wrong" direction. This phenomenon is known as "aileron reversal." Although current aircraft use leading edge "flap devices," these devices are used as high lift devices to optimize lift-to-drag ratio, but not to reduce structural deformation or twisting at high speeds as occasioned by the flap devices of the present invention.